Light-reflecting simmering shutter for high-pressure metal vapor lamps



Nov. 4, 1952 J. B. s. sMYTH 2,617,013 LIGHT-REFLECTING SIMMERING SHUTTER FOR HIGH-PRESSURE METAL VAPOR LAMPS Filed DeC. 51, 1947 N INVENTOR.

JOHN BERNARD SCORE .SMYTH Patented Nov. 4, 1952 FOR .HIGH-PRESSURE METAL LAMPS VAPOR John Bernard Score Smyth, London, England, assignor -t'o The General Electric Company, Limited, London, England Application December 31, 1947, Serial No.. 794,836 In Great Britain November 11, 194.6

Section 1, -PublicLaw 690, August 8, 1946 Tatent .expires November 11, 1966 4 Claims. l

This invention relates to lighting fittings Asuitable for .lighting studios, .stages and the like, where the light source .is a high pressure .metal vapour .(H. P. M. V.) .lam-p, such as a high :pressure mercury vapour lamp which may contain additional metallic vapours introduced to modify the colour rendering of the lamp.

It is well known that when such lamps are switched olif after they have been working., .some

time must .elapse before they .can be made :to

relight unless relatively complicated .means for re-starting .are provided.

In cinema studios and for some other purposes, it .is .required to be 4able to turn the illumination .on and 01T at will and itis `one object of rthe present invention to provide vrelatively simple means whereby this .can be done when the light source is a lamp of the H. P. M. V. type.

According to .one aspect of the present invention, .a lighting fitting suitable .for lighting a studio, stage or the like, `and adapted to voper-ate with .a lamp of the H. PL. M. V. type includes at least .one movable shutter arranged to open and close, the said shutter or shutters being arranged, when closed, .to interrupt the passage of light from the lamp and to co-operate with one .another and/or with .one lor more nxed `members substantially to surround at least -the bulb or `the like .of the lamp.

According to another aspect .of the :present invention a lighting ntting suitable for lighting a studio, stage .or the like and adapted to operate with a lamp oi .the H. M. V. ytype includes at least -one .movable vshutter arranged to open and close, the said .shutter .being arranged, when closed, to interrupt the passage .of light .from the lam-p and to reflect heat radiated by the lamp back to the lamp to assist in keeping the .temperature thereof suiiiciently high for the vapour pressure to be maintained when power supplied to the .lamp is .reduced below its normal roperating value.

The said shutter `or shutters may form part of the optical system .of the fitting.

Means may be provided .for reducing the power supplied to the lamp, when the shutter @rsh-utters are closed while the lamp .is operating to a value suiciently high for the discharge therein `to .be maintained. These means may be mechanically linked with the shutter or shutters v'so that power is automatically reduced when they are closed. Means may also be provided for cutting off the ventilation to the lamp when the :movable shutters .are closed in order to maintain the 'temperature of the :lamp .at a .high value.

The illumination can therefore be turned Idit by moving the said parts into the closed position whilst the power to the lamp is .reduced but not cut ofi. 'The illumination can be .restored almost immediately by opening the said parts and restoring the .full current `to the lamp.

One example of a lighting fitting .in accordance with the present invention will now be described by way of example with reference to the three gures of the accompanying vdiagrammatic drawings in which Figure 1 shows an elevation of the fitting with a side panel removed.; Figure 2 shows a plan of .the fitting with the top cover removed; and .Figure .3 .shows an electric .circuit .for Vthe operation .ofthe lamp.

Referring .now to Figures l and 2 ofthe drawings, the lighting fitting AI comprises .a housing 2 carrying `upper and lower lampholders f3 and 4 respectively for va H. i?. M. V. lamp .'(not shown)- An optical reflector system is associated 'with the lamp and .consists of fa fixed .centre part 5, lixed top and bottom kparts 6 and 1, and hinged side parts 8 and 9. The parts '5 9 .are mounted on a suitable framework (not shown) inside the housing 2. :The two side parts 8 and 9 are 'capable .of `swinging about axes parallel to the axis of `the lamp as hereinafter described.

'When a H. P. M. V. lamp in the fitting I is operating and the reflector parts T8 and 9 are "in the open `position shown in Figure 2, all the parts .--B .form vpart of the reflector system and vvmay combine with other optical elements (not shown) to -g'ive a .desired vciistribution of light from the lamp. When `the illumination is itc vbe tur-ned oi, the power supply to the 'lamp iis reduced and at the same time :the parts 8 and l9 'are 'moved intothe position-shown" and 9' 4'in.Figure..2. The centre part 5 and the side parts 8 and B then form a 'three -sided venclosure around the lamp which is substantially closed at each end thereof by the top and bottom reflector parts 6 and vfl. y

The reflector parts 8 and 9 are closed by ymoving Ya lever l 0 into the open position I-D.. A lever and link mechanism comprising members I"| and l2 is provided between the lever 10 and aparts l8 and 9. Considerable play is provided between the parts of this mechanism and toggle springs I3 and I4 are arranged to hold fthe members 'I2 in .the open or closed position of 'the 'parts 8 and T9, over a dead-centre `position .so that the .parts .8 and 9 open or close with a .snap action. Stops (not shown) may be provided to accurately locate the positions of the parts .8 and B.

A compartment t5 located under the mai-n housing 2 of the iitting contains ancillary elec-.

tric equipment associated with the lamp. The lever I is arranged to operate a switch (not shown) to insert part of a ballast resistor (not shown) in the lamp circuit when the parts 8 and 9 are closed. Alternatively a separate switch may be provided to reduce the power supplied to the lamp. The compartment I5 may also contain electrical and mechanical interlocks arranged so that the main supply cannot be switched on until the parts 8 and 9 are in their closed position S and 9', the interlock mechanism including a relay having an operating coil connected across the lamp, the relay being adapted to prevent the parts 8 and 9 being opened and thus cutting out part of the said ballast resistor until such time as the voltage across the lamp has reached a predetermined value.

A suitable electric circuit for operating the lamp is shown in Figure 3. A lamp 2i) is supplied from an alternating current supply 2i through two resistances 22 and 23 respectively, and a. starting choke coil 24 connected in series. The electric supply to the lamp is controlled by a double pole switch 25. A switch 25 is connected across the resistance 23 to enable it to be short circuited. A relay switch 21 is connected to short circuit the choke coil 2li and is operated by a winding 2S connected to carry the current flowing through the lamp 20. A starting switch 29 is arranged to short circuit the lamp and winding 28 for starting purposes.

To start the lamp the switch Z is closed while switch 26 is open. As no current news in the lamp under these conditions, the relay switch 2i is open. When the starting switch 2t is closed momentarily current fiows through the resistances 22 and 23 and the choke coil 2S. he voltage surge due to the choke coil 25 when the starting switch 29 is opened causes an electric discharge to start through the lamp 2- and draw current through the winding 28 to cause the relay switch 2 to close to short circuit the choke coil 24. While the lamp 20 is warming up to the operating temperature and pressure the switch 2B is open so that reduced power is supplied to the lamp. During this period the shutters or" the fitting are closed around the lamp to conserve heat. When the lamp has reached the normal operating temperature and pressure the resistance 23 can be short circuited by the switch 25 to raise the power input to the normal level and the shutters opened to allow light to be emitted from the tting. If it is desired to cut off the light from the lamp the shutters can be closed and the switch E5 opened to reduce the power supplied to the lamp to a value such that it maintains the lamp at or about its normal operating temperature and pressure so that it may rapidly be brought to normal operation by opening the shutters and restoring the input to the normal value.

I claim:

l. A lighting fitting comprising in combination a lamp housing, means to mount within said housing an electric lamp of the high pressure metal Vapour type, at least one lightand heatrefiecting shutter, means to mount said shutter for pivotal movement in said housing between two` positions in one of which the shutter allows a light beam from the lamp to leave the housing and constitutes a reiiector forming at least a part of the optical system of the iitting, and in the other of which the shutter prevents light from leaving the housing and also reflects back to the lamp heat emanating from the lamp, operating means to move said shutter between its first and second positions, circuit means for reducing power supplied to the lamp while maintaining an electric discharge through the lamp, means to render said circuit means eiective when the shutter is in its second-named position, heat reiiected from the shutter in such position maintaining the temperature of the lamp with the reduced power input substantially at the same temperature as with the shutter in the first-named position with normal power input to the lamp.

2. A lighting fitting comprising in combination a lamp housing, means to mount within said housing an electric lamp of the high pressure metal vapour type, a lightand heat-reiiecting member mounted within said housing, two lightand heat-reflecting shutters, means to mount said shutters, one on each side of the first mentioned reflecting member, for pivotal movement in said housing between two positions in one of which the shutters allow a light beam from the lamp to leave the housing, and in the other of which the shutters prevent light from leaving the housing and co-operate with the first mentioned reiiecting member substantially to surround at least part of the envelope of the lamp to reflect light and heat back to the lamp to maintain the vapour pressure within the lamp envelope when the current to the lamp is below its normal operating value, and operating means to move said shutters between said first and second positions.

3. A lighting fitting comprising in combination a lamp housing, means to mount within said housing an electricl lamp of the high pressure metal vapour type, a lightand heat-reflecting member mounted within said housing, two lightand heat-reflecting shutters, means to mount said shutters, one on each side of the first mentioned reilecting member, for pivotal movement in said housing between two positions in one of which the shutters allow a light beam from the lamp to leave the housing, and in the other of which the shutters prevent light from leaving the housing and co-operate with the first-mentioned reflecting member substantially to surround at least part of the envelope of the lamp to reflect light and heat back to the lamp Ato maintain the vapour pressure within the lamp envelope when the current to the lamp is below its normal operating value, operating means to move said shutters between said rst and second positions, circuit means for reducing power supplied to the lamp while maintaining an electric discharge through the lamp, and means to render said circuit means effective when the shutter is in its second-named position.

4. A lighting tting comprising in combination a lamp housing, means to mount within said housing an electric lamp of the high pressure metal vapour type, a lightand heat-reflecting member mounted within said housing, a first pair of lightand heat-reiiecting members, meansto mount said rst pair of light-reiiecting members within said housing adjacent to two opposite sides of said first reecting member, a second pair of lightand heat-reflecting members, means to mount each of said second pair of members for pivotal movement in said housing about axes adjacent to the other two sides of the rst mentioned reiiecting member, and operating means to eifect rotation of the second pair of reiiecting members between a iirst position in which they co-operate with the rst-mentioned reflecting member and the iirst pair of reflecting members to project light from the housing, and a second position in which the second pair of reflecting members co-operate with the first mentioned refleeting member and the rst pair of reecting members substantially enclose at least part of the envelope of the lamp to prevent light from the lamp leaving the housing and to reflect heat back to the lamp to maintain the vapour pressure within the lamp envelope when the power input to the lamp is below its normal operating value.

JOHN BERNARD SCORE SMYIH.

REFERENCES CITED The following references are of record in the file of this patent:

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